EV-Charging Queues: Reservations, Session Length and Fair-Use Rules

Why queues form and when they are avoidable

A queue is a throughput problem, not simply a capacity problem. On a fast charger, power delivery is non-linear: up to roughly 80% the battery accepts high current, then the vehicle sharply reduces it to protect the pack. A driver who insists on 100% therefore occupies the stall two to three times as long to harvest the slow tail end of the curve, which adds little range. This is why operators, from Circuit Électrique to Electra, encourage an informal "80% rule" on fast stations.

Congestion is usually a peak phenomenon: urban stations in the evening, highway hubs on mass-travel days, retail sites on weekends. Even a few saturated hours can degrade the experience because, in queuing terms, average wait time grows super-linearly with occupancy and with the variance of session length. Cutting average session time and its spread is therefore often a stronger lever than simply adding connectors.

• From 20–30% to ~80–85% a fast session typically takes 20–40 minutes; pushing to 100% adds much more at declining power.
• Queues also worsen when bays are occupied by cars that are not charging at all — internal-combustion vehicles or EVs left plugged after finishing.

Reservations: certainty versus the frozen stall

Booking gives a driver certainty that a connector will be waiting, which matters on long trips or at busy urban sites. The Belarusian network Evika! shows a disciplined model: booking is free for users with a positive balance, but you must plug in within 15 minutes or the reservation is cancelled, and a new booking becomes available only after a successful session. When the chosen station is busy, the app lets you "join the queue" and sends an SMS the moment a connector frees up.

The downside of booking is the "frozen stall": a reserved connector sits physically empty while the holder drives to it, even though other drivers are already waiting on site. That is precisely why some operators are reversing course. French network Electra removed reservations entirely, returning to first-come, first-served on the argument that this guarantees fairer access and maximizes actual use of each connector. If you keep reservations, the mitigation is a short plug-in window, a no-show fee or penalty, and offering booking mainly when utilization is low.

Session length and state-of-charge caps: the 80% lever

Capping target state of charge rather than wall-clock minutes is smarter, because charge time depends on each vehicle's speed. Circuit Électrique asks drivers not to charge above 80% at fast stations unless necessary so the stall frees sooner, and Electra alerts users the moment their vehicle hits 80%. These soft rules change behaviour because many drivers simply do not watch the taper.

Where recommendations are not enough, operators enforce thresholds. On a pilot group of high-demand metropolitan stations, Electrify America automatically ends the session at 85% state of charge and will not even start a session if the battery is already at or above that level; after the stop, drivers have a 10-minute grace period before idle fees begin. Because most EVs charge fast in the bulk band, an 85% cap sharply reduces both the average session time and its variance, which are the two drivers of average waiting time.

• An enforced cap usually lands at 80–85% to capture the bulk charge while keeping stall time short.
• Check the operator's app or site for a stated limit banner before plugging in on a busy network.

Idle fees and bay enforcement done fairly

An idle fee penalizes leaving a car connected after the charge ends or after the target state of charge is reached. To be perceived as fair rather than as a tax, it needs a grace period, a clear in-app notification when charging completes and when fees start, and exemptions matched to context (for example, night hours or hotel guests). Software such as Electric Avenue lets operators trigger idle fees by state of charge in 5% steps from 75 to 100%, recommends capping at 80%, and gives a 15-minute warning after the session before money starts being charged.

A complementary tool is enforcing who may occupy the bay at all. In Moscow, charging sites sit under a "No Stopping" sign with a plate that permits only EVs and plug-in hybrids during a session; parking an internal-combustion car there carries an administrative fine of 4,500 rubles, and the transport authority asks drivers to vacate within 15 minutes of completing a charge. Reported violations fell roughly 30% year on year, suggesting that visible rules plus reporting channels change behaviour. Mature networks also make fees conditional on congestion rather than unconditional, waiving them when the site is not busy.

Price transparency and regulation: the EU context

Fair-use rules only work if prices are legible. Since 13 April 2024, the EU's Alternative Fuels Infrastructure Regulation (AFIR) requires that users can charge and pay ad hoc at publicly accessible points without a prior contract, and that new DC fast chargers above 50 kW accept card payment. Prices must be reasonable, transparent and non-discriminatory, and must be available electronically before a session with every component itemized — energy, connection, any e-roaming costs and any operator fees. Existing fast chargers above 50 kW must be retrofitted for compliance by 2027.

This matters well beyond the EU as a benchmark for fairness: when a driver sees before plugging in exactly what energy, a minute of session, an idle fee or a reservation costs, disputes in a queue become more predictable and behaviour more rational. Operators elsewhere, including in Russia and Belarus, are progressively copying the same toolkit — SMS queues, booking windows and idle fees — even without a single regulation forcing them.

Designing a fair-use policy for your site

There is no universal recipe, but there is a reliable sequence of decisions. Start with the site profile and its peaks: a transit fast-charging hub needs firm caps and idle fees, whereas an overnight slow charger at a residence needs long sessions and minimal penalties. Then choose a target state of charge — usually 80–85% — and decide whether it is a recommendation or an enforced session stop.

Next, design the queue mechanics: plain first-come, first-served, an SMS or in-app queue with notifications, or reservations with a short window and a no-show penalty. Finally, build in transparency and feedback: publish prices before the session, send alerts when charging ends and when a fee will start, post clear signage, and give users a reporting channel for occupied bays. Then treat every rule as provisional and tune it against measured wait time, utilization and dwell time rather than anecdotal complaints.

• Define exemptions per constraint: night hours, reduced-mobility drivers, hotel guests staying longer.
• Announce fees both on the charger and in the app; surprise charges destroy trust.
• Track turnover (sessions per hour) and average wait, not only revenue, when judging a policy.